This application claims the priority benefit of Japanese Patent Application No. 2000-363,528 filed on Nov. 29, 2000, and entitled xe2x80x9cDisk Drive Apparatus, Hard Disk Drive, Filter and Method for Inspecting Disk Drive Apparatus.xe2x80x9d
1. Field of the Invention
The present invention relates to a disk drive apparatus suitable for the hard disk drive (hereinafter, HDD) used as data storage means for computers, and particularly to a head assembly for reading/writing data from/to magnetic disk.
2. Background Art
The HDD, which is the most conventional data storage means for computers, has a structure in which a single or a plurality of magnetic disks are coaxially arranged and driven by a spindle motor. Data recording and writing are carried out by a magnetic head provided opposite to said magnetic disk, which is swung by an actuator, usually a voice coil motor (hereinafter, VCM). The above magnetic disks, magnetic head, and actuator are accommodated in a housing called a disk enclosure. The disk enclosure is formed of a base made of an aluminum alloy shaped in a thin case, and a top cover for sealing the opening of the base.
The storage capacity of a HDD depends on the specification of the computer on which it is mounted, and usually it has a single or plurality of magnetic disks to satisfy the storage capacity. For instance, if the storage capacity demanded of the HDD is 30 GB (gigabytes), three magnetic disks each having a storage capacity of 10 GB are prepared. However, there are various computer specifications, and a product having a HDD of 10 GB also exists. In this case, the disk enclosure and other parts are unified to support a plurality of storage capacities. For instance, the disk enclosure and other parts are previously designed so that a maximum of three magnetic disks each of 10 GB are mounted namely, an HDD of 30 GB is formed, and three magnetic disks are mounted if the required storage capacity is 30 GB, two disks are mounted for 20 GB, and one disk is mounted for 10 GB. Three magnetic disks can be mounted on this HDD, and the HDD that actually has three magnetic disks mounted thereon is called the full population version, while the HDD that actually has two or one disk mounted thereon is called the depopulation version.
In the depopulation version, the number of magnetic disks to be mounted on the HDD is increased or decreased according to the required storage capacity. Then, the number of magnetic heads for reading/writing data from/to magnetic disks is increased or decreased according to the number of magnetic disks. For instance, four magnetic heads are provided if the number of magnetic disks is two, and two magnetic heads are provided if the number of magnetic disks is one. If the number of magnetic heads is decreased, the weight decreases accordingly, which results in deviation of the center of gravity of the actuators to which the magnetic heads are attached. Thus, usually dummy heads are attached to the actuators to maintain their center of gravity.
3. Problems to be Solved by the Invention
By attaching dummy heads, the center of gravity of the actuators including magnetic heads, or of the head assembly can also be made to match the swing shaft in the depopulation version. It is important to cause the center of gravity of the head assembly to match its swing shaft for increasing the accuracy of the magnetic head positioning. FIG. 5 is a perspective view showing the conventional head assembly using dummy heads. In FIG. 5, a head assembly 200 has, as the main structural elements of it, a pivot shaft holder 210, a coil 220 for VCM (voice coil motor) which is attached to the pivot shaft holder 210, arms 231-233 which are attached at positions symmetrical to the coil 220 for VCM with respect to the pivot shaft, suspension arms 241-244 which are attached to the end portions of the arms 231-233, and magnetic heads 251-254 which are attached to the end portions of the suspension arms 241-244.
It is assumed that the head assembly 200 performs data read/write for the HDD having two magnetic disks mounted or the HDD having one magnetic disk mounted as the depopulation version. For the HDD of the full population version on which two magnetic disks are mounted, as shown in the upper portion of FIG. 5, the four suspension arms 241-244 respectively having the magnetic heads 251-254 attached thereto are attached to the arms 231-233. On the other hand, for the HDD of the depopulation version on which only one magnetic disk is mounted, as shown in the lower portion of FIG. 5, dummy heads 261 and 262 are attached where the suspension arms 241 and 242 are to be attached.
The head assembly 200, in which the four suspension arms 241-244 are attached to the arms 231-233, and the head assembly 200, in which the two dummy heads 261 and 262 are attached, are both designed so that the center of gravity matches the swing shaft. However, by attaching the dummy heads 261 and 262, a further resonance frequency affecting the performance of the HDD may occur in the head assembly 200. Accordingly, it is required to adjust the center of gravity of the head assembly 200 without attaching the dummy heads 261 and 262.
In Published Unexamined Utility Model Application No. 5-36655 Specification, there is disclosed a technique for adjusting the center of gravity of a head assembly. In the head assembly disclosed in Published Unexamined Utility Model Application No. 5-36655, a counter weight is fixed by a screw between the pivot shaft and the coil for VCM. However, the technique disclosed in Published Unexamined Utility Model Application No. 5-36655 is primarily intended to adjust the position of the center of gravity if the center of gravity deviates from the swing center of the head assembly. That is, it is not intended to adjust the center of gravity of the depopulation version head assembly.
Accordingly, it is an object of the present invention to provide a head assembly which enables the adjustment of its center of gravity for the depopulation version, while suppressing the occurrence of a resonance frequency affecting the performance of the disk drive apparatus.
In one embodiment of the present invention, the problems described above are solved by attaching a counter weight for adjusting the center of gravity of the head assembly of the depopulation version at a specific position on the head assembly. Accordingly, the present invention is a head assembly swinging over data storage media, the head assembly comprising a head for reading/writing data from/to the data storage media, an arm to which the head is attached, a swing shaft for supporting the arm, a coil for voice coil motor extended from the swing shaft, and a counter weight set at a predetermined position on the swing shaft which is on the side opposite to the coil for voice coil motor with respect to the swing shaft.
Since the counter weight is provided on the swing shaft, the head assembly of the present invention can reduce the occurrence of the vibration due to swing motion as compared with the dummy head attached to the arm, thereby to suppress the occurrence of a resonance frequency affecting the performance of the disk drive apparatus. Further, in the head assembly of the present invention, the counter weight is provided on the side opposite to the coil for the voice coil motor with respect to the swing shaft. This suggests that the counter weight is attached for the depopulation version, but it is not attached for the full population version, as detailed in the section of embodiments.
In the depopulation version, the number of data storage media is reduced from the full population version, and the number of heads is reduced accordingly. Thus, if the head assembly of the present invention is applied to the depopulation version, a plurality of the arms is provided, and there are existing arms to which the head is attached, and arms to which the arm is not attached.
Further, in the head assembly of the present invention, the counter weight can be detachably provided in the swing shaft. Generally, the full population version and the depopulation version share components with one another. This is also the case for the head assembly. Accordingly, if the full population version and the depopulation version share the head assembly, and the counter weight is detachable, then it is only needed to attach the counter weight only for the depopulation version.
Further, in accordance with the present invention, there is provided a head assembly swinging over data storage media, including: a swing shaft as the center of the swing motion; a coil for voice coil motor extended from the swing shaft; an arm extended from the swing shaft in the direction opposite to the coil for voice coil motor; a head attached to the arm for reading/writing data from/to the data storage media; and a counter weight set at a predetermined position on the swing shaft where it gives a moment to the swing shaft in the direction opposite to the direction of the moment effected by the coil for voice coil motor.
In accordance with the head assembly of the present invention, since the counter weight is also provided on the swing shaft, the occurrence of vibration due to the swing motion can be reduced, as compared with the dummy head attached to the arm, and the occurrence of a resonance frequency affecting the performance of the disk drive apparatus can be reduced. The counter weight of the present invention gives a moment in the direction opposite to the direction of the moment effected by the coil for voice coil motor. Accordingly, if the head assembly is of the depopulation version, the positional deviation of the center of gravity caused by the reduction of the magnetic heads can be suppressed.
The present invention provides a disk drive apparatus to which the head assembly of the present invention is applied. That is, the disk drive apparatus of the present invention is a disk drive apparatus in which an N (a positive integer) number of disk-like data storage media can be attached, comprising, an n (a positive integer smaller than N) number of the data storage media, and a swing-type head assembly for reading/writing data from/to the data storage media, the head assembly including, a head for reading/writing data from/to the data storage media, an arm to which the head is attached, a swing shaft for supporting the arm, a coil for voice coil motor extended from the swing shaft, and a counter weight provided on the swing shaft.
The disk drive apparatus of the present invention enables an N (a positive integer) number of data storage media to be attached, but the number of data storage media to be actually attached is n that is smaller than N. Accordingly, the disk drive apparatus includes the depopulation version. Thus, in this case, the heads are attached in a number of 2n. And, since the disk drive apparatus of the present invention allows a counter weight to be provided in the swing shaft in the depopulation version, the occurrence of vibration due to the swing motion can be reduced as compared with the dummy head attached to the arm, and the generation of a resonance frequency affecting the performance of the disk drive apparatus can be suppressed. In addition, the counter weight need not be attached for the full population version. In the disk drive apparatus of the present invention, the counter weight can be set at a position where it gives a moment to the swing shaft in the direction opposite to the direction of the moment effected by the coil for voice coil motor.
Further, in the disk drive apparatus of the present invention, the counter weight can be formed of a single member. The conventional dummy heads are attached in a number corresponding to the heads reduced in the depopulation version as compared with the full population version. On the other hand, in the present invention, the counter weight can be formed of a single member, and thus it is more easily attached as compared with the dummy head.
Further, the present invention provides a hard disk drive in which an N (a positive integer) number of magnetic disks can be attached, including, an n (a positive integer smaller than N) number of the magnetic disks, and a swing-type head assembly for reading/writing data from/to the magnetic disks, the head assembly including, a 2n number of magnetic heads for reading/writing data from/to the magnetic disks, an arm to which the 2N number of magnetic heads can be attached, a swing shaft for supporting the arm, a coil for voice coil motor extended from the swing shaft, and a counter weight set on the swing shaft for giving the same moment of inertia as given when the 2N number of magnetic heads are attached.
Also in the hard disk drive, a counter weight is provided in the swing shaft, so the generation of vibration due to the swing motion can be reduced as compared with the dummy head attached to the arm. And, since the counter weight gives a moment of inertia similar to the full population version in which the 2N number of magnetic disks are attached, it can correct the deviation of the center of gravity in the depopulation version.
Further, the present invention provides a hard disk drive for which the number of magnetic heads for reading/writing data is reduced from that for the hard disk drive as standard, including a magnetic disk for storing data, a head assembly having the magnetic disk and moving above the magnetic disk by swinging around the swing shaft, and a counter weight set in the vicinity of the swing shaft for adjusting the center of gravity of the head assembly. In the hard disk drive of the present invention, since the counter weight is provided in the vicinity of the swing shaft, the occurrence of vibration due to the swing motion can be reduced as compared with the dummy head attached to the arm. In the hard disk drive of the present invention, the counter weight can be specified not to increase the inertia of the head assembly attached to the hard disk drive as standard.
The present invention also provides a method for manufacturing the disk drive apparatus described above. That is, the method for manufacturing a disk drive apparatus of the present invention is a method for manufacturing a disk drive apparatus comprising disk-like media for storing data and a swing-type head assembly for reading/writing data from/to the disk-like media, the disk drive apparatus being capable of having an N (a positive integer) number of said disk-like media stacked therein, the method including the steps of attaching in the vicinity of the swing shaft a counter weight for causing the swing shaft to match the center of gravity in the head assembly if an n (a positive integer smaller than N) number of the disk-like media are stacked, and omitting the attaching of the counter weight if the N number of disk-like media are stacked.
In the method for manufacturing a disk drive apparatus of the present invention, the head assembly has a head for reading/writing data from/to the disk-like media, an arm to which the head is attached, and a swing shaft for supporting the arm, and if the n (a positive integer smaller than N) number of disk-like media are stacked, the counter weight is attached at a predetermined position on the swing shaft where a moment is given in the same direction as the moment caused to act on the swing shaft by the arm.